path: root/080_blog/00015_Miscellanous/index.md

Miscellanous Notes
==================
    
A collection of short notes on things I wish to remember. Many topics are heavily outdated.

Backing up and Restoring Docker Volumes
---------------------------------------

    July 3, 2017

One of my first questions, when starting my docker experience was 
how to backup and restore docker volumes.

### On the source host

First of all identify your volumes:

    $ docker ps
    $ docker inspect my_container_name | grep -C 1 -i Source

Now you can backup the directory to a tar on your host machine:

    $ docker run –rm –volumes-from my_container_name -v $(pwd):/backup ubuntu tar cvf /backup/backup_db.tar /var/lib/mysql

### On the target host

In order to securely copy and restore the volume on the target host one can run:

    $ scp source_host:~/backup_db.tar .
    $ docker run –rm –volumes-frommy_container_name -v $(pwd):/backup ubuntu bash -c “cd /var/lib/mysql && tar xvf /backup/backup_db.tar –strip 1″

A Growing Collection of Linux Command Line One-Liners
------------------------------------------------------

Please believe me... this collection was really supposed to grow over time...

inside a direcotry show disk usage of all hidden files and directories and sort by size:

    $ du $(ls .* -d | tail -n +3) -hs |sort -h

inside a direcotry show disk usage of all files and directories (also hidden) and sort by size.
Exclude ./DATA file.

    $ du . -a -d 1 -h –exclude=’./DATA’ | sort -h

Tar all files in current directory, excluding ./DATA and ./.cache

    $ tar –exclude=’./.cache’ –exclude=’./DATA’ -cvf home_miguel_20180216.tar .

Find files in ./ARCHIVE NOT belonging to a specific user: miguel

    $ find ARCHIVE/ \! -user miguel

set folder/ permissions to Read/Browse only for owner recursively

    $ sudo chmod -R u=r,g=,o= folder/
    $ chmod -R u=rX,g=,o= folder/

find all mails from Boban when in the maildir full of mailboxes and print only short headers without bodies:

    $ grepmail -H -B -Y ‘(^TO:|^From:)’ Boban *

not really a one-lier but will print 256 colors in a bash:

    for i in {0..255} ; do
        printf "\x1b[48;5;%sm%3d\e[0m " "$i" "$i"
        if (( i == 15 )) || (( i > 15 )) && (( (i-15) % 6 == 0 )); then
            printf "\n";
        fi
    done

Some Tools of Choice
--------------------

### Systems

* joomla
* redaxo
* typo3
* wordpress
* mediawiki

* oscommerce
* opencart

* owncloud
* alfresco
* mantis

* piwik / matomo
* loganalyzer
* goaccess
* nagios / icinga

### Servers

* apache
* nginx

* mariadb / mysql
* postfix
* postgis

* geoserver

<!--
## Tools / Servers
    openlayers
    git / gitweb / stagit / gitolite
    xmpp
    mumble
    docker / registry
    kvm
    kubernetes
    postfix/dovecot / rouncube/postfixadmin
    symfony
    bootstrap
    webGL
    websockets
    ajax
    node/angular
    jmeter
    ceph
-->

Compilation Notes
-----------------

### build your own webkit

    March 14, 2018

Let’s compile a release with debug info and install to /usr/local

~~~~~~ {.bash}
wget https://webkitgtk.org/releases/webkitgtk-2.20.0.tar.xz
tar -xvf webkitgtk-2.20.0.tar.xz
cd webkitgtk-2.20.0
# install all the libs that will be reported missing in the next step.
# I could not find the woff2 stuff in debian so skipped it... 
cmake -DPORT=GTK -DCMAKE_BUILD_TYPE=RelWithDebInfo -DUSE_WOFF2=NO -GNinja
# this takes about 30minutes on my i7-4790K .. zzzzz..zzz
ninja
sudo ninja install
~~~~~~~~~~~

    pkg-config

    pkg-config uses our new build now:

    [1] https://trac.webkit.org/wiki/BuildingGtk
    [2] https://webkitgtk.org/

### Build and Install GCC

    April 27, 2015

#### Preparations
Read the prequisites at 
[https://gcc.gnu.org/install/prerequisites.html](https://gcc.gnu.org/install/prerequisites.html) 
and get (most recent versions at time of  this writing) the following:

* gcc (5.2.0)
* binutils (2.25.1)

#### Configure and Build

* unpack binutils-x.y.z
* create a new directory binutils-x.y.z-build and inside it run the following commands:

~~~~~~ {.bash}
    $ ../binutils-x.y.z/configure --disable-nls --with-sysroot --enable-targets=all
    $ make -j4
    $ make install
~~~~~~~~~~~~

* unpack gcc-x.y.z and run the contrib/download_prerequisites script inside.
* create a new directory: gcc-x.y.z-build and inside it run:
    
~~~~~~ {.bash}
    $ ../gcc-x.y.z/configure --disable-nls --enable-languages=c,c++ --enable-threads
    $ make -j4
    $ make install
~~~~~~~~~~~~

#### Reference
    [1] binutils and gcc README files.
    [2] https://gcc.gnu.org/install/
    [3] http://wiki.osdev.org/Building_GCC
    [4] http://stackoverflow.com/questions/1726042/recipe-for-compiling-binutils-gcc-together

monad transformers in action
----------------------------
    January 1,2018 
    
    *Main Control.Monad.Writer Control.Monad.State> runState (runWriterT  (get >>= \a -> tell ["foo"] >> put (a*a) >> tell ["bar"] >> tell [show a])) 5

emscripten
----------
    October 1,2017

    sdl2 port
    https://github.com/juj/emsdk
    android-ndk-r15c

    * accomplish build sys with: sdl2+input+audio+opengl+SDL_net+SDL_thread @ linux, win, osx, ios, android, win-phone, steam, rasp

LUKS container over sshfs
-------------------------
    July 5, 2017

* enable user\_allow\_other in /etc/fuse.conf
* sshfs -o allow\_root user@server:/BACKUPS/ ~/mnt/
* dd if=/dev/urandom of=~/mnt/megaloman bs=1M count=512
* sudo cryptsetup -y luksFormat ~/mnt/megaloman
* sudo cryptsetup luksOpen ~/mnt/megaloman vol1
* sudo mkfs.ext4 /dev/mapper/vol1
* sudo mount /dev/mapper/vol1 /mnt
* df -h | grep vol1
* sudo umount /mnt
* sudo cryptsetup luksClose vol1
* fusermount -u ~/mnt

NOTE: backup your data example use : rsync -a –info=progress2 source dist

some areas of interest
----------------------
    December 20, 2014

Some General Topics I am reasearching right now (or plan to do it). Or used to reasearch...

* Neuronal Networks
* Deep Learning
* Random Forrests (and other techniques based on Decision Trees)
* Simmulated Annealing
* (Linear) Integer Programming


Inter Process Communication
---------------------------
    March 14, 2018

We can attach nicely to same memory segment from 2 different processes:

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ {.c .numberLines}
// ipc via shared mem
// attach to shared memory;
key_t my_ftok = ftok("~/surf-webext-dom-shared-mem",'a');
 
int mem_seg=shmget(my_ftok,1024*1024,IPC_CREAT|0660);
if(mem_seg==-1)
{
g_print("shmget failed: %s\n",strerror(errno));
}
 
shared_buf=shmat(mem_seg,NULL,0);
if(shared_buf==(void*)-1)
{
g_print("shmat failed: %s\n",strerror(errno));
}
g_print("attached to shared memory.\n");
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

SSL Certificate CSR
-------------------
    
    February 20, 2015

    for apache ssl mod

    first check your old csr if you like:
    $ openssl req -text -noout -verify -in CSR.csr
    
    1. generate key
    $ openssl genrsa -des3 -out www.yourdomain-example.com.key 2048
    
    2. create CSR
    $ openssl req -new -key www.yourdomain-example.com.key -out www.yourdomain-example.com.csr
    
    refs:
    [1] https://search.thawte.com/support/ssl-digital-certificates/index?page=content&id=AR1108&actp=LIST

Competitive Coding
------------------
    March 17, 2015

A small selection of websites, which I visit from time to time, addressing competitive coding.

* topcoder.com
* codeforces.com
* codility.com
* codersclan.ne
* projecteuler.net
* www.codingame.com (need to check this)
* www.codechef.com (need to check this)
* http://psyho.gg/overview-of-programming-contests/ (and read here)
* https://www.hackerrank.com/
* http://code.google.com/codejam
* https://www.kaggle.com/ – predicitve modelling
* odesk.com / elance

Comp Science Literature
-----------------------
    March 17, 2015
This is a list of some books, focusing on topics around computer science, which I recently read or am currently reading or want to read :P

* Meyers, Effective C++ (Addison-Wesley) C++98 only?
* Meyers, More Effective C++ (Addison-Wesley) C++98 only?
* Meyers, Effective STL. C++98 only?
* Sutter, Exceptional C++
* Sutter, More Exceptional C++
* Karlson, Beyond the C++ Standard Library: An Introduction to Boost 1st Edition
* Maybe Something on Multiprocessing (?)
* Donald Knuth. The Art Of Computer Programming
* Algorithms 3rd Edition (by Cormen, Leiserson, Rivest, Stein)
* Jonathan Bartlett. Programming from the Ground Up
* C++ in a Nutshell (O’REILLEY, by Lischner)
* C++ Primer (5th Edition) by Lippman, Lajoie, Moo
* The C++ Programming Language 4th Edition
* Anthony Williams, C++ Concurrency in Action: Practical Multihreading
* Dive into Python (2 and 3) by Mark Pilgrim
* Learn You a Haskell for Great Good by Marian Lipovaca
* Real World Haskell
* Version Control with Git (O’REILLEY, by Loeliger & McCullough) (next: 9(10) ?)
* The Linux Command Line, by William Shotts (http://linuxcommand.org/tlcl.php)
* Debian, The Administrators Handbook (by Hertzog and Mas)
* Absolute FreeBSD by Michael W. Lucas
* Modern Operating Systems, Third Edition (by Andrew S. Tannebaum)
* Linux Device Drivers (O’REILLEY, by Corbert, Rubini, Kroah-Hartman)
* Linux Kernel in a Nutshell (O’REILLEY,  Greg Kroah-Hartman)

* Concrete Math (2nd)
* UPENN cis194

* STOC '83 Proceedings of the fifteenth annual ACM symposium on Theory of computing / Primitives for the manipulation of general subdivisions and the computation of Voronoi diagrams

* http://haskellbook.com/
* Wadler paper "Monads for Functional Programming"
* simon marlow - book (parallel)
* data 6 - course (Github)
* sedgewick & waynes algorithms
* books from appendix, from programming from ground up?

VNC
---
    April 2, 2015

### Server:
    $ apt-get install tightvncserver
    $ xtightvncserver -geometry 1900×1100
    $ netstat -tap | grep vnc # remember port (e.g.5901)

### Client:
    $ ssh -L 5901:localhost:5901 you@remote # tunnel
    $ xtightvncviewer localhost::5901 # in new terminal

### Kill Server:
    $ vncserver -kill :1 # (or :2 etc..)

Owncloud Notes
--------------

### Mounting Ownclouds DavFS

    April 15, 2015

    $ apt-get install davfs2

    * since owncloud seems to have problems with locks, edit /etc/davfs2/davfs2.conf and set use_locks to 0 in order to allow creating files (as well as probably writing)

    $ mount -t davfs https://secure.sf.com/owncloud/remote.php/webdav /mnt/

### rescan/rebuild ownlocud files database

    June 22, 2016

    inside ownlcoud  directory run:
    sudo -u www-owncloud php console.php files:scan –all


LXC
---
    April 28, 2015

    maybe worth a try:

    apt-get install lxc; lxc create ctname -t download — -d debian -r jessie
    -a amd64; lxc-start -d -n ctname, lxc-attach ctname

    similar tools: chroot/ debootsrap

Add vim Lang
------------
    May 14, 2015 

    $ sudo apt-get install myspell-pl
    $ cd /ush/share/hunspell
    $ vim
    :mkspell pl pl_PL

What every programmer should know about
---------------------------------------
    November 7, 2015

    Undefined behaviour: http://blog.llvm.org/2011/05/what-every-c-programmer-should-know.html
    Memory: http://lwn.net/Articles/250967/
    Floating point arithmetic: https://docs.oracle.com/cd/E19957-01/806-3568/ncg_goldberg.html

IDE Comparison
--------------

    December 7, 2015

While I love working with vim (ctags, taglist, etc..) and the command line, it might be worth to have a look at the following IDE’s for Java and/or C++:

* IntelliJ IDEA
* Eclipse
* Eclipse CDT
* Codeblocks
* Netbeans
* Codelite
* KDevelop

Setup Postfix
-------------

We want to handle different domains on a single postfix server and have virtual users along real unix users. For the virtual users we use uid/gid 5000.

Relevant config files are:

    /etc/postfix/master.cf
    /etc/postfix/main.cf
    /etc/postfix/smtpd_sender_login_maps (tells which emails belong to which login)
    /etc/postfix/vmailbox (sepcifies our VIRTUAL mailboxes and the names of the spoolfiles)
    /etc/postfix/virtual (aliases for our local unix users)
    /etc/dovecot/users (specifies the logins, passwords, home directories,..)
    /etc/dovecot/conf.d/10-mail (set inbox and mailbox dirs)

Be careful about the permissions of the different folders, so uid/gid 5000, postfix and dovecot can access as relevant.

A very nice tutorial on setting up postfixadmin can be found here: 

    https://lelutin.ca/posts/installing_postfix_-_clamav_-_spamassassin_-_dovecot_-_postfixadmin_on_debian_squeeze/

Windows Specific Notes
----------------------

### disable hiberfile.sys

    September 7, 2017

    run cmd.exe as administrator:
    powercfg.exe -h off

### GTA4 on NVIDIA-GTX 980

    April 17, 2016

    Add following flags : -nomemrestrict -norestriction
    Otherwise video memory is not identified correctly.

### Civilization 4 BTS Autosaves

    September 23, 2016

    In the file: C:\Users\miguel\Documents\My Games\Beyond the Sword\CivilizationIV

    Adjust:

    ; The maximum number of autosaves kept in the directory before being deleted.
    MaxAutoSaves = 100

    ; Specify the number of turns between autoSaves. 0 means no autosave.
    AutoSaveInterval = 1